remove temporary bookmaker files

remove temporary bookmaker files

Add checks to bookmaker so it doesn't write status
if generated files are unchanged; and deletes temporary
files in working directory.

TBR=caryclark@google.com

Bug: skia:6898
Change-Id: Id4e8dec78a4febfdf2a0a466fceef1024ff4859d
Reviewed-on: https://skia-review.googlesource.com/151546
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
3 files changed